The demand for efficiency improvements in energy storage systems is driving the development of batteries with higher energy density, increased depth of discharge, a longer cycle life and a lighter, flexible form factors. Most current research effort is directed towards Li-ion batteries (LIBs) because of their inherent higher energy density compared to other types of rechargeable battery chemistries, and negligible memory effect after numerous charge-discharge cycles. Thus, for the past twenty years, significant resources have been directed on improving electrochemical performance of the active electrode materials, developing safer electrodes and electrolytes, and lowering the manufacturing cost of LIBs. However, LIBs are designed to meet specific application requirements and a tradeoff is often made between various parameters such as high energy density vs. high power, charge-discharge rate vs. capacity and cycle life, safety vs. cost etc. These tradeoffs become necessary, primarily due to the limitations imposed by the electrochemical properties of the active materials, electrolyte, and separator as well as battery manufacturing methods.
Lithium ion batteries (LIBs) in various shape and size are widely used in various kinds of portable electronic devices, medical devices and are being considered for use in electric vehicle as well for use in solar power systems, smart electricity grids and electric tools. However, current state of the art (SOA) Li-ion battery technology is limited in terms of energy capacity, charging speed and manufacturing cost. Based on Department of Energy (DOE) reports, ten years of effort, and billions in spending on Li-ion battery development, the manufacturing cost of LIBs has not decreased significantly and is still three to six times higher than the DOE target ($700/kWh-current vs. $150/kWh-target). Also, performance of Li-ion battery has not improved as expected especially for scalable manufacturing platforms. A key contributor to the price stagnation and performance plateau is continued reliance on the same traditional battery manufacturing technology using roll-to-roll foil lamination that was developed over 20 years ago. Another contributing factor is the synthesis of the powder based active electrode material which constitutes 40-50% of the battery cost. Thus, a new battery design and manufacturing paradigm is required to address cost issues. Also, the state of art graphite anode based Li-ion battery technology is limited in terms of energy capacity, charging speed and safety. Because of limited anode capacity, batteries require charging more often. Competitive anode solutions have not overcome fundamental challenges resulting in limited calendar life as well as slow charging.
It has been reported that annealing of the cathode material on a substrate under proper conditions improves battery performance, as elevated temperature annealing causes the cathode material to crystallize. However, elevated temperature annealing increases the cost of cathode manufacturing. Thus, what is needed is to provide, for example, a low cost cathode manufacturing method having desired crystal structure for improved performance and safety.
Lithium-ion batteries are inherently not safe due to foil based structure where a large amount of energy is stored. Damage to the battery can lead to a short circuit releasing large amounts of energy and resulting in thermal runaway, fire, and explosion.
Thus, next generation Li-ion batteries require, for example, a cost effective continuous manufacturing method for battery and battery component as well as, for example, a higher capacity anode solution with fail-safe battery design.